MIAMI – Dontrelle Willis had owned the Mets entering last night, and Kaz Ishii hadn’t owned a victory since last Aug. 29.

So naturally, the baseball world was turned upside down when Willie Randolph’s resurgent club derailed the “D Train” while Ishii was flummoxing the Marlins for a 6-1 victory.

Unless Josh Beckett takes the mound wearing a Braves uniform today, the visitors just might pull off an improbable four-game road sweep that will erase the sour taste of a three-game broom job in Atlanta.

Buoyed by Ishii’s solid 62/3-inning effort and Mike Piazza’s first three runs batted in since May 9, the Mets beat Willis for the first time in eight career starts. Ishii (1-3) allowed five hits and one earned run and only walked three against three strikeouts to secure his first win in 11 starts.

Willis (8-2) stood first in the National League in wins entering the day, and second with a 1.55 ERA. But the Mets (26-24) had no problem hitting him, rapping eight hits through the first five frames.

In the fourth, Cliff Floyd ripped a leadoff single to left and David Wright followed with a double to right, sending Floyd to third. Willis almost escaped when Victor Diaz lined out to first and Wright was caught off second for a double play.

But Ishii helped his own cause, parachuting an RBI single in front of Juan Encarnacion in center to put his club up 1-0.

In the fifth, Piazza escaped a ridiculously long RBI drought of 60 plate appearances, driving in his first run in nearly three weeks. The Mets catcher stroked a one-out double to the fence in right to plate Miguel Cairo, who had singled and stole second to lead off the frame. That double snapped Piazza’s 1-for-16 skid on this road trip.

Piazza followed with an RBI single to left-center in the seventh to spark a three-run Met inning, and a ground-rule RBI double to right in the eighth.

What did Piazza and Ishii have in common? Before the game, Randolph offered a defense of both players.

Piazza, it seemed, looked a little run down with his usual backup, Ramon Castro, on the disabled list. He hadn’t sat out an entire game since May 14. Randolph actually moved him up to cleanup with the southpaw Willis hurling.

Entering yesterday, the walk-happy Ishii had issued 323 career free passes in 502 innings. But Randolph said he didn’t put much stock in the pitcher’s previous performance.

Ishii had walked 18 men in 29 innings since he was acquired in a trade from the Dodgers. But last night, the Met lefty made the Marlins earn it; he was virtually untouchable until Jeff Conine’s RBI double to deep center in the seventh.

Conine was erased trying to stretch it into a triple, which snuffed Florida’s best rally.

The Mets’ offense bludgeoned a punch-drunk Frank Castillo on Thursday and edged the surprisingly game five-and-dimer Brian Moehler on Friday. Some thought their performances were aberrations after that demoralizing sweep in Atlanta, a mirage that would evaporate when Willis took the hill. It didn’t.

Cairo has been a nice surprise since Kaz Matsui (neck strain) went down, although anyone who watched the Yankees in 2004 knew he could do the job. He’s played in eight consecutive games, going 12-for-34 during that span.

He scored three runs and stole two bases and seems to be a Randolph favorite.